Fresnel projection screen and projection system

ABSTRACT

A Fresnel projection screen includes: a Fresnel layer; a first micro-structure layer disposed at a light incident side of the Fresnel layer, the first micro-structure layer including a plurality of micro-structures that are configured to diffusely reflect a portion of light incident thereon and refract another portion of the light; a second micro-structure layer disposed on a surface of the first micro-structure layer, the second micro-structure layer including a plurality of second micro-structures that are configured to diffusely reflect a portion of light incident thereon and refract another portion of the light; and a reflective layer disposed on a side of the Fresnel layer away from the first micro-structure layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of U.S. patentapplication Ser. No. 17/036,685 filed Sep. 29, 2020, which is a BypassContinuation-in-Part Application of PCT/CN2019/075617 filed Feb. 20,2019, which claims priority to Chinese Patent Application No.201810338500.4 filed Apr. 16, 2018, Chinese Patent Application No.201810339425.3 filed Apr. 16, 2018, Chinese Patent Application No.201810393661.3 filed Apr. 27, 2018, and Chinese Patent Application No.201810444670.0 filed May 10, 2018, which are incorporated herein byreference in their entirety.

TECHNICAL FIELD

Some embodiments of the present disclosure relates to a Fresnelprojection screen and a projection system.

BACKGROUND

In the field of projection display technologies, especially in the fieldof ultra-short focus laser projection display technologies, a projectoris generally used with a Fresnel projection screen. The screen hascharacteristics of high gain and small viewing angle, which may improvebrightness to a maximum extent when the screen is viewed directly byhuman eyes. The screen has a certain resistance to ambient light, andhas a good display effect.

SUMMARY

In a first aspect, some embodiments of the present disclosure provide aFresnel projection screen. The Fresnel projection screen includes aFresnel layer, a first micro-structure layer, a second micro-structurelayer and a reflective layer. The first micro-structure layer isdisposed at a light incident side of the Fresnel layer. The firstmicro-structure layer includes a plurality of micro-structures that areconfigured to diffusely reflect a portion of light incident thereon andrefract another portion of the light. The second micro-structure layeris disposed on a surface of the first micro-structure layer, and thesecond micro-structure layer includes a plurality of secondmicro-structures that are configured to diffusely reflect a portion oflight incident thereon and refract another portion of the light. Thereflective layer is disposed on a side of the Fresnel layer away fromthe first micro-structure layer.

In a second aspect, some embodiments of the present disclosure provide aprojection system. The projection system includes a projector and theFresnel projection screen described above. The projector is configuredto project light onto the Fresnel projection screen. The Fresnelprojection screen is configured to receive the light projected by theprojector and to display a corresponding image.

In a third aspect, some embodiments of the present disclosure provide aFresnel projection screen. The Fresnel projection screen includes atransparent layer, a color layer, a diffusion layer and a Fresnel layerarranged in sequence along a light incident direction. The transparentlayer includes a transparent base and a micro-structure layer. Themicro-structure layer is disposed on a light incident surface of thetransparent base. The micro-structure layer is configured to diffuselyreflect a portion of light incident thereon and refract another portionof the light. The micro-structure layer includes a plurality of firstmicro-structures and a plurality of second micro-structures disposed ona surface of the plurality of first micro-structures. A dimension ofeach first micro-structure is greater than a dimension of each secondmicro-structure. The dimension includes at least one of a width, lengthor thickness of a micro-structure.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe technical solutions in embodiments of the presentdisclosure more clearly, the accompanying drawings to be used in thedescription of the embodiments will be introduced briefly. However, theaccompanying drawings to be described below are merely some embodimentsof the present disclosure, and a person of ordinary skill in the art canobtain other drawings according to these drawings without paying anycreative effort.

FIG. 1 is a diagram showing how a Fresnel projection screen reflectslight;

FIG. 2 is a diagram showing how a Fresnel projection screen reflectslight to form images;

FIG. 3A is a schematic diagram of a Fresnel projection screen, inaccordance with some embodiments;

FIG. 3B is a schematic diagram of another Fresnel projection screen, inaccordance with some embodiments;

FIG. 4A is a schematic diagram of yet another Fresnel projection screen,in accordance with some embodiments;

FIG. 4B is a schematic diagram of yet another Fresnel projection screen,in accordance with some embodiments;

FIG. 4C is a schematic diagram of yet another Fresnel projection screen,in accordance with some embodiments;

FIG. 5A is a schematic diagram of yet another Fresnel projection screenincluding a micro-structure layer having a multilayer structure, inaccordance with some embodiments;

FIG. 5B is a schematic diagram of yet another Fresnel projection screenincluding a micro-structure layer having a single-layer structure, inaccordance with some embodiments;

FIG. 6 is a perspective view of the micro-structure layer in the Fresnelprojection screen shown in FIG. 5A;

FIG. 7 is a diagram showing a variation of the micro-structure layer inthe Fresnel projection screen shown in FIG. 5A;

FIG. 8A is a diagram showing another variation of the micro-structurelayer in the Fresnel projection screen shown in FIG. 5A;

FIG. 8B is a schematic diagram of yet another Fresnel projection screenincluding a micro-structure layer having a single-layer structure, inaccordance with some embodiments;

FIG. 8C is a perspective view of the micro-structure layer shown in FIG.8B;

FIG. 9A is a diagram showing yet another variation of themicro-structure layer in the Fresnel projection screen shown in FIG. 5A;

FIG. 9B is a schematic diagram of yet another Fresnel projection screenincluding a micro-structure layer having a single-layer structure, inaccordance with some embodiments;

FIG. 9C is a perspective view of the micro-structure layer shown in FIG.9B;

FIG. 10 is a schematic diagram showing a support layer added on thebasis of the Fresnel projection screen shown in FIG. 5A;

FIG. 11 is a schematic diagram showing another support layer added onthe basis of the Fresnel projection screen shown in FIG. 5A;

FIG. 12 is a schematic diagram showing support layers added on the basisof the Fresnel projection screen shown in FIG. 5A;

FIG. 13 is a diagram showing an anti-ambient light principle of aFresnel projection screen;

FIG. 14 is a schematic diagram of a spectrally selective layer of aFresnel projection screen, in accordance with some embodiments;

FIG. 15 is a schematic diagram of a spectrally selective layer ofanother Fresnel projection screen, in accordance with some embodiments;

FIG. 16 is a schematic diagram of a spectrally selective layer of yetanother Fresnel projection screen, in accordance with some embodiments;

FIG. 17 is a schematic diagram of yet another Fresnel projection screen,in accordance with some embodiments;

FIG. 18 is a graph showing a transmittance of a spectrally selectivelayer of a Fresnel projection screen, in accordance with someembodiments;

FIG. 19 shows an arrangement of RGBW;

FIG. 20 shows a mosaic arrangement of RGB;

FIG. 21 shows a triangular arrangement of RGB;

FIG. 22 shows a straight-bar arrangement of RGB;

FIG. 23 shows a four-pixel arrangement of RGB;

FIG. 24 is a schematic diagram of yet another Fresnel projection screen,in accordance with some embodiments; and

FIG. 25 is a schematic diagram of a projection system, in accordancewith some embodiments.

DETAILED DESCRIPTION

The technical solutions in some embodiments of the present disclosurewill be described clearly and completely below with reference to theaccompanying drawings in some embodiments of the present disclosure.However, the described embodiments are merely some but not allembodiments of the present disclosure. All other embodiments made on thebasis of some embodiments of the present disclosure by a person ofordinary skill in the art without paying any creative effort shall beincluded in the protection scope of the present disclosure.

It will be understood that, in the description of some embodiments ofthe present disclosure, orientations or positional relationshipsindicated by the terms “center”, “upper”, “lower”, “front”, “rear”,“left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”,“outer”, etc. are based on orientations or positional relationshipsshown in the drawings, merely to facilitate and simplify the descriptionof the present disclosure, but not to indicate or imply that thereferred devices or elements must have a particular orientation, or mustbe constructed or operated in a particular orientation. Therefore, theseterms should not be construed as limitations to the present disclosure.

The terms such as “first” and “second” are used for descriptive purposesonly and are not to be construed as indicating or implying the relativeimportance or implicitly indicating the number of indicated technicalfeatures. Thus, features defined as “first”, “second” may explicitly orimplicitly include one or more of the features. In the description ofsome embodiments of the present disclosure, the term “a plurality of”means two or more unless otherwise specified.

“Substantially” or “approximately” as used herein is inclusive of thestated value and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system). For example, “Substantially” or “approximately” canmean within one or more standard deviations, or within ±30%, 20%, 10% or5% of the stated value.

“And/or” as used herein includes three situations: only A, only B, and Aand B.

FIG. 1 is a diagram showing how a Fresnel projection screen reflectslight. As shown in FIG. 1, when light emitted by a projector 01 entersthe screen 02 from air, due to a difference between a refractive indexof a material of the projection surface of the screen 02 and arefractive index of air, a portion of the light (i.e., the light beam x)is specularly reflected by the projection surface of the screen 02 to aregion near the screen 02, such as a ceiling, and another portion of thelight (i.e., the light beam y), which is refracted, enters the screen 02for imaging.

FIG. 2 is a diagram showing how a Fresnel projection screen reflectslight to form images. As shown in FIG. 2, when the projector 01 projectsa preset image with preset colors onto a projection surface of theFresnel projection screen 02, a portion of light emitted by theprojector 01 enters the screen 02 to form the preset image, and anotherportion of the light is specularly reflected by the projection surfaceof the screen 02 and travels to the ceiling 03. When colors at positionsa, b and c on the projection surface of the screen 02 are different,colors at corresponding positions A, B and C on the ceiling 03 are alsodifferent. As a result, an image with low brightness and similar to thepreset image is formed on the ceiling 03.

It will be noted that a light incident side of the Fresnel projectionscreen refers to a side thereof from which the light enters the Fresnelprojection screen. A light incident side of a layer in the Fresnelprojection screen herein refers to a side of the layer closer to thelight incident side of the Fresnel projection screen than the oppositeside of the layer. A light incident surface of a layer in the Fresnelprojection screen herein refers to a surface of the layer closer to thelight incident side of the Fresnel projection screen than the oppositesurface of the layer.

As shown in FIG. 6, a vertical direction OY used herein may refer to avertical direction when the Fresnel projection screen is placedvertically and is in use, such as the width direction of the Fresnelprojection screen. A horizontal direction OZ may refer to a horizontaldirection when the Fresnel projection screen is placed vertically and isin use, such as the length direction of the Fresnel projection screen. Athickness direction OX, the vertical direction OY and the horizontaldirection OZ may perpendicular to each other. On this basis, the crosssection used herein may be a section parallel to a plane defined by thevertical direction OY and the thickness direction OX. A cross section ofa micro-structure is, for example, a cross section passing through theapex of the micro-structure.

FIGS. 3A to 4C are schematic diagrams of Fresnel projection screensaccording to some embodiments, and show micro-structures in the Fresnelprojection screens.

As shown in FIGS. 3A to 4C, the Fresnel projection screen includes aFresnel layer 203 and a transparent layer 100 disposed at a lightincident side of the Fresnel layer 203.

As shown in FIG. 3A, the Fresnel layer 203 is, for example, a Fresnellens, which has a plurality of micro-structures, such as grooves, formedin a surface thereof facing away from the transparent layer 100.

The transparent layer 100 is, for example, transparent, and allows lightto pass through. A refractive index of the transparent layer 100 may bewithin a range from approximately 1.3 to approximately 1.8, such as,1.3, 1.4, 1.5, 1.6, 1.7 or 1.8. The transparent layer 100 may be made oftransparent plastic. For example, the transparent layer 100 includes atransparent base 201 and the material of the transparent base 201includes at least one of polycarbonate (PC), polyethylene terephthalate(PET), styrene-co-methyl methacrylate (MS), or polymethyl methacrylate(PMMA).

The transparent layer 100 includes, for example, the transparent base201 and a micro-structure layer disposed on a light incident surface(also called a first surface 2011 hereinafter) of the transparent base201. The micro-structure layer is configured such that a portion oflight is refracted when entering the micro-structure layer through itslight incident surface, and another portion of the light is diffuselyreflected when incident on the light incident surface of themicro-structure layer. The refracted light enters the Fresnel layer 203to form the preset image. Since the diffusely reflected light may notgather in a specific region, the reflected light may not form an imagesimilar to the preset image near the screen.

In some embodiments, as shown in FIGS. 3A and 3B, the micro-structurelayer includes a first micro-structure layer, and the firstmicro-structure layer includes a plurality of first micro-structures 21.

In some examples, as shown in FIG. 3A, a thickness of each firstmicro-structure 21 is the same. The thickness of the firstmicro-structure 21 may refer to a maximum distance between a surface ofthe first micro-structure 21 facing away from the transparent base 201and the first surface 2011 of the transparent base 201 facing the firstmicro-structure 21 in the thickness direction of the Fresnel layer 203(i.e., the thickness direction OX in FIG. 3A). If the firstmicro-structure 21 and the transparent base 201 are integrally formed,the thickness of the first micro-structure 21 may refer to a maximumdistance between the surface of the first micro-structure 21 facing awayfrom the transparent base 201 and a surface of the transparent base 201facing away from the first micro-structure 21 in the thickness directionof the Fresnel layer 203 (i.e., the thickness direction OX in FIG. 3A).

In some other examples, the thicknesses of some of the plurality offirst micro-structures 21 are the same. In some other examples, thethicknesses of two adjacent first micro-structures 21 are different. Insome other examples, as shown in FIG. 3B, the thicknesses of theplurality of first micro-structures 21 are randomly set. Of course, thethicknesses of the first micro-structures 21 are not limited thereto,and may be set according actual needs. For example, the thicknesses oftwo adjacent first micro-structures 21 are the same, but are differentfrom thicknesses of other first micro-structures 21.

In some examples, as shown in FIG. 3A, a width of each firstmicro-structure 21 is the same. The width of the first micro-structure21 refers to a maximum dimension of an orthographic projection of thefirst micro-structure 21 on the transparent base 201 in the verticaldirection OY.

In some other examples, the widths of some of the plurality of firstmicro-structures 21 are the same. In some other examples, the widths oftwo adjacent first micro-structures 21 are different. In some otherexamples, as shown in FIG. 3B, the widths of the plurality of firstmicro-structures 21 are randomly set. Of course, the widths of the firstmicro-structures 21 are not limited thereto, and may be set accordingactual needs. For example, the widths of two adjacent firstmicro-structures 21 are the same, but are different from widths of otherfirst micro-structures 21.

In some examples, as shown in FIG. 3A, a length of each firstmicro-structure 21 is the same. The length of the first micro-structure21 refers to a maximum dimension of the orthographic projection of thefirst micro-structure 21 on the transparent base 201 in the horizontaldirection OZ.

In some other examples, the lengths of some of the plurality of firstmicro-structures 21 are the same. In some other examples, the lengths oftwo adjacent first micro-structures 21 are different. In some otherexamples, as shown in FIG. 3B, the lengths of the plurality of firstmicro-structures 21 are randomly set. Of course, the lengths of thefirst micro-structures 21 are not limited thereto, and may be setaccording actual needs. For example, the lengths of two adjacent firstmicro-structures 21 are the same, but are different from lengths ofother first micro-structures 21.

In some examples, as shown in FIG. 3A, a segment Q of an outer border ofthe cross section of the first micro-structure 21 facing away from thetransparent base 201 is one segment of an arc such as a circle, anellipse, a parabola, a hyperbola or a free curve, and is smooth. In someexamples, the first micro-structure 21 is a protrusion or a groove. Theprotrusion is, for example, an arc-shaped protrusion, a columnarprotrusion, a prismatic protrusion, or a conical frustum shapedprojection.

For example, the orthographic projection of the first micro-structure 21on the transparent base 201 is in a shape of a circle, and the crosssection of the first micro-structure 21 passing through its apex is in ashape of a semicircle. In this case, the thickness of the firstmicro-structure 21 is its radius, and the width and the length of thefirst micro-structure 21 are both its diameters.

For another example, as shown in FIG. 3A, the segment Q of the outerborder of the cross section of the first micro-structure 21 facing awayfrom the transparent base 201 is a segment of the circle. For example,as shown in FIG. 3B, the segment of the outer border of the crosssection of the first micro-structure 21 facing away from the transparentbase 201 is a segment of the free curve.

In some examples, as shown in FIG. 3A, the shape of each firstmicro-structure 21 is the same. In some other examples, the shapes ofsome of the plurality of first micro-structures 21 are the same. In someother examples, the shapes of two adjacent first micro-structures 21 aredifferent. In some other examples, as shown in FIG. 3B, the shapes ofthe plurality of first micro-structures 21 are randomly set. Of course,the shapes of the first micro-structures 21 are not limited thereto, andmay be set according actual needs. For example, the shapes of twoadjacent first micro-structures 21 are the same, but are different fromshapes of other first micro-structures 21.

In some examples, as shown in FIG. 3A, the plurality of firstmicro-structures 21 are distributed uniformly. In some other examples,some of the plurality of first micro-structures 21 are distributeduniformly, and remaining first micro-structures 21 are distributedrandomly. In some other examples, the plurality of firstmicro-structures 21 are distributed randomly. The distribution of theplurality of first micro-structures 21 is not limited thereto, and maybe designed according to actual needs.

In some examples, as shown in FIGS. 3A and 3B, the plurality of firstmicro-structures 21 are distributed continuously, and completely coversthe transparent layer 201.

In some examples, as shown in FIG. 3A, the plurality of firstmicro-structures 21 have a same length, a same width, a same thicknessand a same shape, which may facilitate processing and make the lightscattering more uniform.

In some other examples, as shown in FIG. 3B, lengths, widths,thicknesses and shapes of the plurality of first micro-structures 21 arerandomly set. In this way, due to the randomness of the structure, thelight scattering may be more uniform, and the colors and brightness ofthe light at different positions on the ceiling 400 or the object at aside of the screen may be basically consistent, thereby blurring theimage on the ceiling 400 to a greater extent.

In this case, for example, the plurality of first micro-structures 21are projections, and the plurality of first micro-structures 21 aredistributed continuously. In this way, the transition of the projectionsmay be smoother, and the light scattering may be improved.

In some other examples, the plurality of first micro-structures 21include a plurality of first-type first micro-structures 21 and aplurality of second-type first micro-structures 21. The plurality offirst-type first micro-structures 21 have a same shape, a same width, asame length and a same thickness. The plurality of second-type firstmicro-structures 21 have a same shape, a same width, a same length and asame thickness.

For example, multiple second-type first micro-structures 21 are providedbetween every two adjacent first-type first micro-structures 21. Alongthe vertical direction OY and/or the horizontal direction OZ,second-type first micro-structures 21 disposed at two sides of afirst-type first micro-structure 21 are symmetrically distributedrelative to the center of the first-type first micro-structure 21.

In some other examples, the plurality of first micro-structures 21include a plurality of first-type first micro-structures 21 and aplurality of second-type first micro-structures 21. Multiple second-typefirst micro-structures 21 are provided between every two adjacentfirst-type first micro-structures 21. The plurality of first-type firstmicro-structures 21 have a same shape, a same width, a same length and asame thickness. Shapes, widths, lengths and thicknesses of the pluralityof second-type first micro-structures 21 are randomly set.

In some embodiments, a difference between thicknesses of any two of theplurality of first micro-structures 21 is within a range fromapproximately 5 μm to approximately 100 μm, such as 5 μm, 15 μm, 25 μm,35 μm, 45 μm, 55 μm, 65 μm, 75 μm, 85 μm, 95 μm, or 100 μm. In this way,the appearance of the first micro-structures 21 may be smoother, andproblems such as easy dirt and accumulation of dust caused by groovesmay be avoided.

An excessive curvature radius of the first micro-structure 21 may affectthe scattering effect of the light. A too small curvature radius of thefirst micro-structure 21 may make it very difficult to form thetransparent layer 100. Therefore, in some examples, the curvature radiusof the first micro-structure 21 is within a range from approximately 30μm to approximately 500 μm, such as 30 μm, 100 μm, 150 μm, 200 μm, 250μm, 300 μm, 350 μm, 400 μm, 450 μm, or 500 μm. In this way, thescattering effect of the light may be ensured, and the difficulty offorming the transparent layer 100 may be reduced.

In some examples, the plurality of first micro-structures 21 are formedon the transparent base 201 through an injection molding process, acompression molding process or a coating process. In actual processing,the micro-structure layer may be formed through roll-to-roll extrusioncoating by rollers. In this way, continuous production may be realized,and the production yield and efficiency may be high. For anotherexample, the micro-structure layer may be formed through the compressionmolding process by flat-sheet molds. This molding process is easy. Insome other examples, the plurality of first micro-structures 21 and thetransparent base 201 are integrally formed through the injection moldingprocess, and are made of a same material.

As shown in FIGS. 3A and 3B, the micro-structure layer may be theoutermost layer of the Fresnel projection screen. In the micro-structurelayer, the first micro-structures 21 are light diverging structures.Therefore, by adjusting the shape of the first micro-structure 21, it ispossible to control a ratio of light refracted at the firstmicro-structure 21 to light reflected at the first micro-structure 21.In this case, a portion of light emitted by the projector 300 may passthrough the first micro-structure 21 and enter the Fresnel layer 203,thereby displaying an image normally.

In the embodiments, the plurality of first micro-structures 21 aredistributed on the light incident surface of the transparent base 201.Therefore, as shown in FIGS. 3A and 3B, light at a same position on aceiling 400 or light at a same position on an object at a side of theFresnel projection screen is formed by superposition of light scatteredby the first micro-structures 21 at different positions on thetransparent base 201. For example, as shown in FIGS. 3A and 3B, lightscattered by the first micro-structures 21 at three different positionson the transparent base 201 is superimposed at one point on the ceiling400. Therefore, the Fresnel projection screen in some embodiments of thepresent disclosure may prevent the image similar to the preset imagefrom being formed on the ceiling 400 or on the object at the side of theFresnel projection screen.

In addition, the light is scattered to regions around the Fresnelprojection screen in all directions without being reflected to aspecific region. Therefore, the Fresnel projection screen in someembodiments of the present disclosure may reduce light reflected ontothe ceiling 400 or light reflected onto the object at the side of theFresnel projection screen, thereby reducing brightness of the reflectedlight.

In some other embodiments, as shown in FIGS. 4A to 4C, themicro-structure layer includes a first micro-structure layer and asecond micro-structure layer disposed on a surface of the firstmicro-structure layer facing away from the transparent base 201. Thefirst micro-structure layer includes a plurality of firstmicro-structures 21, and the second micro-structure layer includes aplurality of second micro-structures 22.

As shown in FIGS. 4A to 4C, the micro-structure layer may be theoutermost layer of the Fresnel projection screen. In the micro-structurelayer, the first micro-structures 21 and the second micro-structures 22are all light diverging structures. Therefore, by adjusting shapes ofthe first and second micro-structures, it is possible to control a ratioof light refracted at the micro-structure to light reflected at themicro-structure. In this case, a portion of light emitted by theprojector 300 may pass through the first and second micro-structures andenter the Fresnel layer 203, thereby displaying an image normally.

In the embodiments, the first and second micro-structures 21 and 22 aredistributed on the light incident surface of the transparent base 201.Therefore, as shown in FIGS. 4A to 4C, light at a same position on aceiling 400 or light at a same position on an object at the lightincident side of the Fresnel projection screen is formed bysuperposition of light scattered by the first and secondmicro-structures 21 and 22 at different positions on the transparentbase 201. For example, as shown in FIGS. 4A to 4C, light scattered bythe first micro-structures 21 and the second micro-structures 22 atthree different positions on the transparent base 201 is superimposed atone point on the ceiling 400. Therefore, the Fresnel projection screenin some embodiments of the present disclosure may prevent the imagesimilar to the preset image from being formed on the ceiling 400 or onthe object at the side of the Fresnel projection screen.

In addition, the light is scattered to regions around the Fresnelprojection screen in all directions without being reflected to aspecific region. Therefore, the Fresnel projection screen in someembodiments of the present disclosure may reduce light reflected ontothe ceiling 400 or light reflected onto the object at the side of theFresnel projection screen, thereby reducing brightness of the reflectedlight.

The Fresnel projection screen is, for example, a front projectionscreen, and as shown in FIG. 4A, the projector 300 may be placed below acenter perpendicular line of the Fresnel projection screen at the lightincident side of the Fresnel projection screen.

It will be noted that the descriptions of the first micro-structure 21and the second micro-structure 22 in different embodiments can bereferred to each other, and the similarities thereof may not bedescribed again.

The micro-structure layer in some embodiments will be described belowwith reference to FIGS. 4A to 4C.

In some examples, a thickness of each second micro-structure 22 is thesame. The thickness of the second micro-structure 22 refers to athickness of the second micro-structure 22 at its apex. In an examplewhere the second micro-structure 22 is the second micro-structure A inFIG. 4A, a surface of the second micro-structure 22 facing away from thetransparent base 201 and a straight line PP′ passing through the apex ofthe second micro-structure 22 and perpendicular to the surface of theadjacent first micro-structure 21 facing away from the transparent base201 have a first intersection point, and a surface of the adjacent firstmicro-structure 21 facing away from the transparent base 201 and thestraight line PP′ have a second intersection point. The distance betweenthe first intersection point and the second intersect point is thethickness of the second micro-structure 22. In this case, the straightline PP′ is perpendicular to the surface of the transparent base 201facing away from the first micro-structure 21.

In some other examples, the thicknesses of some of the plurality ofsecond micro-structures 22 are the same. In some other examples, thethicknesses of two adjacent second micro-structures 22 are different. Insome other examples, as shown in FIG. 4B, the thicknesses of theplurality of second micro-structures 22 are randomly set. Of course, thethicknesses of the second micro-structures 22 are not limited thereto,and may be set according actual needs. For example, the thicknesses oftwo adjacent second micro-structures 22 are the same, but are differentfrom thicknesses of other second micro-structures 22.

In some examples, as shown in FIGS. 4A to 4C, a thickness of the firstmicro-structure 21 is greater than a thickness of the secondmicro-structure 22. In this way, a scattering effect of the light may befurther improved. Of course, the thickness of the first micro-structure21 may be equal to the thickness of the second micro-structure 22.

In some examples, a width of each second micro-structure 22 is the same.The width of the second micro-structure 22 refers to a maximum dimensionof an orthographic projection of the second micro-structure 22 on aplane perpendicular to its thickness direction along a directionsubstantially parallel to the vertical direction OY. In the examplewhere the second micro-structure 22 is the second micro-structure A inFIG. 4A, a width of the second micro-structure 22 refers to a maximumdimension of an orthographic projection of the second micro-structure 22on the transparent base 201 in the vertical direction OY.

In some other examples, the widths of some of the plurality of secondmicro-structures 22 are the same. In some other examples, the widths oftwo adjacent second micro-structures 22 are different. In some otherexamples, as shown in FIG. 4B, the widths of the plurality of secondmicro-structures are randomly set. Of course, the widths of the secondmicro-structures 22 are not limited thereto, and may be set accordingactual needs. For example, the widths of two adjacent secondmicro-structures 22 are the same, but are different from widths of othersecond micro-structures 22.

In some examples, as shown in FIGS. 4A to 4C, the width of the firstmicro-structure 21 is greater than the width of the secondmicro-structure 22. Of course, the width of the first micro-structure 21may also be less than the width of the second micro-structure 22.

In some examples, a length of each second micro-structure 22 is thesame. The length of the second micro-structure 22 refers to a maximumdimension of the orthographic projection of the second micro-structure22 on the plane perpendicular to its thickness direction along adirection substantially parallel to the horizontal direction OZ. In theexample where the second micro-structure 22 is the secondmicro-structure A in FIG. 4A, the length of the second micro-structure22 refers to a maximum dimension of the orthographic projection of thesecond micro-structure 22 on the transparent base 201 in the horizontaldirection OZ.

It will be noted that depending on the position of the secondmicro-structure 22 on the first micro-structure 21, the lengthdirection, the width direction and the thickness direction of the secondmicro-structure 22 may change, but the essence of the definitions of thelength, the width and the thickness will not change. With regard toother second micro-structures 22 except the second micro-structure A,reference may be made to the definition of the second micro-structure Ain FIG. 4A.

In some other examples, the lengths of some of the plurality of secondmicro-structures 22 are the same. In some other examples, the lengths oftwo adjacent second micro-structures 22 are different. In some otherexamples, as shown in FIG. 4B, the lengths of the plurality of secondmicro-structures 22 are randomly set. Of course, the lengths of thesecond micro-structures 22 are not limited thereto, and may be setaccording actual needs. For example, the lengths of two adjacent secondmicro-structures 22 are the same, but are different from lengths ofother second micro-structures 22.

In some examples, as shown in FIGS. 4A to 4C, the length of the firstmicro-structure 21 is greater than the length of the secondmicro-structure 22. Of course, the length of the first micro-structure21 may also be equal to the length of the second micro-structure 22.

In some examples, the plurality of second micro-structures 22 aredistributed uniformly. In some other examples, some of the plurality ofsecond micro-structures 22 are distributed uniformly, and remainingsecond micro-structures 22 are distributed randomly. In some otherexamples, the plurality of second micro-structures 22 are distributedrandomly. The distribution of the plurality of second micro-structures22 is not limited thereto, and may be designed according to actualneeds.

In some examples, the first micro-structure 21 is selected from a groupconsisting of an arc-shaped protrusion, a conical frustum, a column, acone, a prism, a groove and a combination thereof. The secondmicro-structure 22 is selected from a group consisting of an arc-shapedprotrusion, a conical frustum, a column, a cone, a prism, a groove and acombination thereof.

For example, the first micro-structure 21 and the second micro-structure22 are arc-shaped protrusions, and the orthographic projections of thefirst micro-structure 21 and the second micro-structure 22 on the firstsurface 2011 are both in a shape of a circle. In this case, the lengthsand widths of the first micro-structure 21 and the secondmicro-structure 22 are all diameters.

For another example, the first micro-structure 21 and the secondmicro-structure 22 are columns, and the orthographic projections of thefirst micro-structure 21 and the second micro-structure 22 on the firstsurface 2011 are both in a shape of a square. In this case, the lengthsand widths of the first micro-structure 21 and the secondmicro-structure 22 are all side lengths.

When the first micro-structure 21 and the second micro-structure 22 haveother shapes, their dimensions changes accordingly with their shapes.

As shown in FIGS. 4A to 4C, for example, the first micro-structure 21and the second micro-structure 22 are both protrusions, such asarc-shaped protrusions, and a curvature radius of the secondmicro-structure 22 is less than a curvature radius of the firstmicro-structure 21.

It will be noted that, an excessive curvature radius of the firstmicro-structure 21 and an excessive curvature radius of the secondmicro-structure 22 may affect the scattering effect of the light. A toosmall curvature radius of the first micro-structure 21 and a too smallcurvature radius of the second micro-structure 22 may make it verydifficult to form the transparent layer 100. In some examples, thecurvature radius of the first micro-structure 21 is within a range fromapproximately 30 μm to approximately 500 μm, and the curvature radius ofthe second micro-structure 22 is within a range from approximately 10 μmto approximately 100 μm. In this way, the scattering effect of the lightmay be ensured, and the difficulty of forming the transparent layer 100may be reduced.

For example, the curvature radius of the first micro-structure 21 may be30 μm, 50 μm, 100 μm, 200 μm, 300 μm, 400 μm, or 500 μm. For example,the curvature radius of the second micro-structure 22 may be 10 μm, 30μm, 50 μm, 70 μm, 90 μm, or 100 μm.

In some embodiments, as shown in FIGS. 4A to 4C, the firstmicro-structure 21 is substantially different from the secondmicro-structure 22. For example, the first micro-structure 21 and thesecond micro-structure 22 are compared in terms of thickness, length,width, shape, distribution and other factors. If there are difference(s)in one or more of these factors, it is considered that the firstmicro-structure 21 is different from the second micro-structure 22.

In some examples, as shown in FIGS. 4A to 4C, the length, width andthickness of the second micro-structure 22 are less than the length,width and thickness of the first micro-structure 21, respectively. Inthis case, the shapes of the first micro-structure 22 and the secondmicro-structure 21 may be the same or different. It will be noted that,each of the shapes of the first micro-structure 22 and the secondmicro-structure 21 refers to the shape of an outer surface composed ofits surfaces except its surface touching the transparent base 201.

For example, as shown in FIG. 4A, the plurality of secondmicro-structures 22 completely cover the first micro-structure layer. Inthis case, multiple second micro-structures 22 may completely cover afirst micro-structure 21, and the multiple second micro-structures 22are symmetrical with respect to the central axis of the firstmicro-structure 21 along the horizontal direction OZ and/or the verticaldirection OY of the Fresnel projection screen. For example, as shown inFIG. 4A, in a cross section passing through the center of the firstmicro-structure 21, the second micro-structures 22 on the firstmicro-structure 21 are symmetrical with respect to the central axis NN′of the first micro-structure 21 along the vertical direction OY of theFresnel projection screen. The central axis NN′ may be a line joining anapex of the first micro-structure 21 and a center of the side of thefirst micro-structure 21 touching the transparent base 201. For example,the first micro-structure 21 has rotational symmetry with respect to itscentral axis NN′.

In this case, for example, the plurality of first micro-structures 21have a same shape, a same length, a same thickness and a same width. Foranother example, some of the plurality of first micro-structures 21 havea same shape, a same length, a same thickness and a same width. Ofcourse, the plurality of first micro-structures 21 may have other shapesand sizes.

In addition, for example, the plurality of second micro-structures 22have a same shape, a same length, a same thickness and a same width. Foranother example, some of the plurality of second micro-structures 22have a same shape, a same length, a same thickness and a same width. Ofcourse, the plurality of second micro-structures 22 may have othershapes and sizes.

In addition, for example, as shown in FIG. 4A, in the thicknessdirection OX of the Fresnel layer 203, a maximum distance between asurface of at least one second micro-structure 22 facing away from thetransparent base 201 and the first surface 2011 of the transparent base201 is greater than a maximum distance between a surface of the firstmicro-structure 22 facing away from the transparent base 201 and thefirst surface 2011 of the transparent base 201.

For another example, as shown in FIG. 4B, the plurality of secondmicro-structures 22 completely cover the first micro-structure layer. Inthis case, multiple micro-structures 22 can completely cover the firstmicro-structure 21. The plurality of first micro-structures 21 have asame shape, a same length, a same width, and a same thickness. Shapes,lengths, widths and thicknesses of the plurality of secondmicro-structures 22 are randomly set. Due to the randomness of thestructure, the light scattering may be more uniform, and the colors andbrightness of the light at different positions on the ceiling 400 or anobject at a side of the screen may be basically the same, therebyblurring the image to a greater extent.

For another example, as shown in FIG. 4C, the plurality of secondmicro-structures 22 cover a portion of the first micro-structure layer.In this case, multiple second micro-structures 22 may only cover theside surface of the first micro-structure 21, and are symmetrical withrespect to the central axis of the first micro-structure along ahorizontal and/or vertical direction of the Fresnel projection screen.The side surface of the first micro-structure 21 may refer to a portionof an outer surface of the first micro-structure 21 that lies on theleft and right of the first micro-structure 21 as viewed from the frontor back. In this way, the transition of the micro-structures may besmoother, and the light scattering effect may be improved.

In this case, for example, the plurality of first micro-structures 21have a same shape, a same length, a same width and a same thickness. Theplurality of second micro-structures 22 have a same shape, a samelength, a same width and a same thickness. Of course, the plurality offirst micro-structures 21 and the plurality of second micro-structures22 may have other shapes and other sizes. For example, the shapes,lengths, widths and thicknesses of the plurality of secondmicro-structures 22 are randomly set.

In addition, for example, as shown in FIG. 4C, in the thicknessdirection of the Fresnel layer 203, a maximum distance between thesurface of the second micro-structures 22 facing away from thetransparent base 201 and the first surface 2011 of the transparent base201 is less than a maximum distance between the surface of the firstmicro-structure 21 facing away from the transparent base 201 and thefirst surface 2011 of the transparent base 201.

In the above embodiments, the plurality of first micro-structures 201may completely cover the transparent base 201, or only cover a portionof the transparent base 201.

In some other examples, at least two first micro-structures 21 have asame shape, a same thickness, a same length and a same width, and atleast two second micro-structures 22 have a same shape, a samethickness, a same length, and a same width.

In the above embodiments, the plurality of first micro-structures 21 mayhave a same shape, a same thickness, a same width and a same length. Theplurality of second micro-structures 22 may have a same shape, a samethickness, a same width and a same length. In this way, on the one hand,the first and second micro-structures 21 and 22 of the Fresnelprojection screen may be easily formed, and on the other hand, the lightmay be scattered uniformly. Therefore, colors of light at differentpositions on the ceiling 400 or on the object at the side of the Fresnelprojection screen may basically tend to be the same. Further, the formedimage is blurred to a great extent.

In some other examples, the plurality of first micro-structures 21 havea same shape, a same thickness, a same width and a same length, andshapes, thicknesses, widths and lengths of the plurality of secondmicro-structures 22 are randomly set.

In some examples, the transparent base 201, the first micro-structures21 and the second micro-structures 22 are integrally formed. In thisway, the molding method may be simple and it may be easy to realize themolding.

In some examples, as shown in FIGS. 4B and 4C, the plurality of firstmicro-structures 21 and the plurality of second micro-structures 22 areintegrally formed. The plurality of first micro-structures 21 and theplurality of second micro-structures 22 can be formed throughroll-to-roll extrusion coating by rollers. In this way, continuousproduction may be realized, and the production yield and efficiency maybe high. In some other examples, the plurality of first micro-structures21 and the plurality of second micro-structures 22 may be formed throughthe compression molding process by flat-sheet molds. This moldingprocess may be easy.

In some other examples, the plurality of first micro-structures 21 andthe transparent base 201 are integrally formed, and are made of a samematerial. The plurality of second micro-structures 22 are coated on thefirst micro-structures 21, and are made of a material different fromthat of the first micro-structures 21.

For example, the plurality of first micro-structures 21 are formedthrough an injection molding process, a compression molding process or acoating process, and the plurality of second micro-structures 22 areformed through the coating process. In this way, the plurality of firstmicro-structures 21 and the plurality of second micro-structures 22 maybe easily formed.

In some other embodiments, the micro-structure layer has the multilayerstructure, and includes first micro-structure layers each including thefirst micro-structures 21, and second micro-structure layers eachincluding the second micro-structures 22. At least one firstmicro-structure layer and at least one second micro-structure layer arealternately arranged. For example, one first micro-structure layer andone second micro-structure layer are alternately arranged, or multiplefirst micro-structure layers and multiple second micro-structure layersare alternately arranged.

In some examples, all first micro-structures 21 in a same layer have asame shape, a same thickness, a same length and a same width, and allsecond micro-structures 22 in a same layer have a same shape, a samethickness, a same length and a same width.

In some other examples, at least two first micro-structures 21 in thesame layer have different shapes, and at least two secondmicro-structures 22 in the same layer have different shapes. Forexample, at least two first micro-structures 21 in the same layer have acombined shape of a conical frustum shape, a columnar shape and aconical shape, and at least two second micro-structures 22 in the samelayer have a combined shape of an arc protrusion shape, a conicalfrustum shape and a columnar shape.

In some embodiments, a segment of an outer border of the cross sectionof each of the first micro-structure 21 and the second micro-structure22 away from the transparent base 201 is one segment of an arc such as acircle, an ellipse, a parabola, a hyperbola or a free curve, and issmooth.

In some examples, a difference between thicknesses of the firstmicro-structure 21 and the second micro-structure 22 is within a rangefrom approximately 5 μm to approximately 100 μm, such as 5 μm, 15 μm, 25μm, 35 μm, 45 μm, 55 μm, 65 μm, 75 μm, 85 μm, 95 μm, 100 μm. In thisway, the appearance of the first micro-structures 21 may be smoother,and problems such as easy dirt and accumulation of dust caused bystructural grooves may be avoided.

In the Fresnel projection screen of some embodiments, if the thickness Pof the transparent layer 100 is too small, it may be difficult to makemold opening. Moreover, if the thickness P of the transparent layer 100is too large, the material may be wasted, it may be difficult to carrythe Fresnel projection screen, and the light loss may be increased.Therefore, in some examples, the thickness P of the transparent layer100 is within a range from approximately 100 μm to approximately 1000μm. In this way, on the one hand, the difficulty of the mold opening maybe reduced; on the other hand, the material may be saved, the Fresnelprojection screen may be easily carried, and the optical loss may bereduced.

The thickness P of the transparent layer 100 refers to a maximumdistance between a surface of the transparent layer 100 facing away fromthe Fresnel layer 203 and a surface of the transparent layer 100 facingthe Fresnel layer 203 in the thickness direction OX of the Fresnel layer203.

For example, the thickness P of the transparent layer 100 may be 100 μm,200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, or 1000μm.

In these embodiments, the micro-structure layer is the outermost layerof the Fresnel projection screen, i.e., disposed on a light incidentside of the transparent base 201. For example, a back face of thetransparent base 201 (a surface of the transparent base 201 facing awayfrom the projector 300) in the transparent layer 100 is bonded to anoptical layer that is closer to the inside of the Fresnel projectionscreen than the transparent layer 100 via an optical adhesive, such asan optically clear adhesive (OCA) or silica gel. For example, thetransparent base 201 may be replaced with the optical layer.

With continued reference to FIGS. 4A to 4C, in some embodiments, theFresnel projection screen further includes a diffusion layer 202 betweenthe transparent layer 100 and the Fresnel layer 203. The diffusion layer202 is capable of homogenizing light beams. A surface of the Fresnellayer 203 away from the diffusion layer 202 is a reflective surface. TheFresnel layer 203 is configured such that obliquely incident light beamsare reflected by the surface of the Fresnel layer 203 away from thediffusion layer 202 at a horizontal viewing angle.

With continued reference to FIG. 4A, in some embodiments, the Fresnelprojection screen further includes a color layer 206 between thetransparent layer 100 and the diffusion layer 202. The optical layerdescribed above may be the color layer 206, the diffusion layer 202 orthe Fresnel layer 203. The transparent base 201 is bonded to the colorlayer 206. The color layer 206 is configured to have differenttransmittances to light of different wavelengths, so that the Fresnelprojection screen may restore primary colors of the preset image to amaximum extent.

In some embodiments, the Fresnel projection screen further includes aprotective layer disposed at a light incident side of the color layer206. The transparent base 201 is bonded to the protective layer. Theprotective layer (with high transmittance) is configured to have awaterproof performance and an impact resistance.

FIGS. 5A to 12 shows some other Fresnel projection screens according tosome embodiments of the present disclosure, in which at least onemicro-structure layer is disposed inside each Fresnel projection screen.As shown in FIGS. 5A to 12, the Fresnel projection screen includes thetransparent base 201, the diffusion layer 202, the Fresnel layer 203 anda reflective layer 204 that are arranged in the light incidentdirection. The Fresnel projection screen further includes at least onemicro-structure layer 205. Each micro-structure layer 205 is configuredto converge a transmission angle of the light. The at least onemicro-structure layer 205 may be disposed between the transparent base201 and the diffusion layer 202, and/or between the diffusion layer 202and the Fresnel layer 203.

For example, as shown in FIGS. 5A, 5B, 8A, 8B, 9A, 9B, and 10 to 12, theat least one micro-structure layer 205 includes one micro-structurelayer 205, which is located between the diffusion layer 202 and theFresnel layer 203. For another example, as shown in FIG. 7, the at leastone micro-structure layer 205 includes one micro-structure layer 205,which is located between the transparent base 201 and the diffusionlayer 202. For another example, the at least one micro-structure layer205 includes two micro-structure layers 205, one of which is disposedbetween the diffusion layer 202 and the Fresnel layer 203, and the otheris disposed between the transparent base 201 and the diffusion layer202. The micro-structure layer 205 is configured to converge the lightreaching the Fresnel layer 203, and thus the micro-structure layer 205may be provided at any position on an optical path of the lighttravelling to the Fresnel layer 203.

It will be noted that the descriptions of the Fresnel projection screenin different embodiments may refer to each other, and similaritiesthereof are not described again.

FIGS. 5A to 7 and 10 to 12 show examples in which the micro-structuresin the micro-structure layer 205 are arc-shaped protrusions. FIGS. 8A to8C show examples in which the micro-structures in the micro-structurelayer 205 are pyramids. FIGS. 9A to 9C show examples in which themicro-structures in the micro-structure layer 205 are prismatic bodies.It will be noted that FIGS. 5A to 12 only show part of shapes of themicro-structures in the micro-structure layer 205. The micro-structuresin the micro-structure layer 205 may have other shapes, and thearrangements thereof can be referred to the related embodimentsdescribed with reference to FIGS. 5A to 12.

In some examples, as shown in FIGS. 5A to 7, the at least onemicro-structure layer 205 is disposed at at least one side of thediffusion layer 202. Each micro-structure layer 205 includes at leastthe first micro-structure layer, and the first micro-structure layerincludes first protrusions 2051 extending in the horizontal direction OZof the Fresnel projection screen.

For example, as shown in FIGS. 5A and 6, the micro-structure layerfurther includes the second micro-structure layer disposed on a surfaceof the first micro-structure layer away from the diffusion layer 202.The second micro-structure layer includes second protrusions 2052extending in the horizontal direction OZ of the Fresnel projectionscreen. The first protrusions 2051 and the second protrusions 2052 areconfigured to converge the incident light along the vertical directionOY of the Fresnel projection screen.

In will be noted that, if the protrusions extend in a direction in whicha viewing angle needs to be enlarged, the viewing angle in thisdirection may be enlarged. As such, the viewer has a large movementrange within the viewing angle, and the image on the Fresnel projectionscreen may be clearly viewed within the viewing angle. For example, inpractical applications, the viewer moves in the horizontal direction OZparallel to ground. Therefore, a wide viewing range in the horizontaldirection OZ parallel to the ground is needed, and a requirement for aviewing range in the vertical direction OY perpendicular to the groundis not high. In this case, an extending direction of the protrusions maybe set as the horizontal direction OZ of the Fresnel projection screen,so that the viewing angle in the vertical direction OY of the Fresnelprojection screen is reduced to obtain a large viewing angle in thehorizontal direction OZ.

The transmission paths of the light beams are described below withreference to FIGS. 5A and 5B, in which solid arrows represent opticalpaths in the Fresnel projection screen that includes the micro-structurelayer 205, and dotted arrows represent optical paths in the Fresnelprojection screen that does not include the micro-structure layer 205.

As shown in FIGS. 5A and 5B, light beams a1 that are emitted by theprojector 300 pass through the transparent base 201, and then enter thediffusion layer 202. The light beams a1 are homogenized under adiffusion effect of the diffusion layer 202. If the micro-structurelayer 205 is not provided, the light beams a1 will directly enter theFresnel layer 203, and are reflected by the reflective surface of theFresnel layer 203 to exit though the light incident surface of thetransparent base 201. A range covered by light beams a1′ that finallyexit is a viewing range where the viewer may view the image on theprojection screen, for example, a range shown by dotted lines a1′.

In a case where the micro-structure layer 205 is provided between thediffusion layer 202 and the Fresnel layer 203, light beams a2 that areemitted by the projector 300 and pass through the transparent base 201are diffused by the diffusion layer 202, and then enter the firstprotrusions 2051. The first protrusions 2051 converge the light beams a2in the vertical direction OY of the Fresnel projection screen. Then, thelight beams a2 enter the second protrusions 2052 (if there are secondprotrusions 2052), and the second protrusions 2052 converge the lightbeams a2 in the vertical direction OY of the Fresnel projection screen.After the light beams a2 are reflected by the reflective surface of theFresnel layer 203, the viewing angle covered by light beams a2′ thatfinally exit in the vertical direction OY becomes small. According tothe law of conservation of energy, if the viewing angle in the verticaldirection OY becomes small, the viewing angle in the horizontaldirection OZ perpendicular to the vertical direction OY may become largeaccordingly, or brightness when the image is viewed in the horizontaldirection OZ perpendicular to the vertical direction OY may increaseaccordingly.

In addition, as shown in FIG. 6, the first protrusions 2051 and thesecond protrusions 2052 included in the micro-structure layer 205 arearranged in parallel. The first and second protrusions have the sameextending direction, and all extend in the horizontal direction OZ ofthe Fresnel projection screen. In this way, the incident light may beconverged in the vertical direction OY of the Fresnel projection screen,thereby enlarging the viewing angle in the horizontal direction OZ.

In some examples, as shown in FIG. 6, in the vertical direction OY ofthe Fresnel projection screen, a width W1 of the first protrusion 2051and a width W2 of the second protrusion 2052 are equal. For example, inthe vertical direction OY of the Fresnel projection screen, a width W1of each first protrusion 2051 and a width W2 of each second protrusion2052 are equal. Herein, the width of a protrusion refers to a distancebetween two edges of a maximum cross section of the protrusion in thevertical direction OY of the Fresnel projection screen. In other words,the width W of a protrusion refers to a maximum dimension of theorthographic projection of the protrusion on the diffusion layer 202 inthe vertical direction OY of the Fresnel projection screen.

For example, as shown in FIG. 6, the width W1 of the first protrusion2051 refers to a dimension of the orthographic projection of the firstprotrusion 2051 on the diffusion layer 202 in the vertical direction OYof the Fresnel projection screen, and the width W2 of the secondprotrusion 2052 refers to a maximum dimension of the orthographicprojection of the second protrusion 2051 on the diffusion layer 202(such as a distance between two points where the surface of the secondprotrusion 2052 and the surfaces of two adjacent first protrusion 2051intersect) in the vertical direction OY of the Fresnel projectionscreen. In this way, the difficulty of forming the transparent layer 100may be reduced.

For example, as shown in FIG. 6, the width W1 of the first protrusion2051 and the width W2 of the second protrusion 2052 may be set to bewithin a range from approximately 10 μm to approximately 500 μm, such as10 μm, 100 μm, 200 μm, 300 μm, 400 μm, or 500 μm.

Considering a current manufacturing process, the width of amicro-structure in the Fresnel layer 203 are generally within a rangefrom approximately 10 μm to approximately 200 μm, such as 10 μm, 30 μm,50 μm, 70 μm, 90 μm, 120 μm, 150 μm, 180 μm or 200 μm. Therefore,corresponding to each micro-structure in the Fresnel layer 205, thewidth of the first protrusion 2051 and the width of the secondprotrusion 2052 in the micro-structure layer may be set to be the sameas the width of the micro-structure in the Fresnel layer 2052 to ensurethe converging effect of the micro-structure layer.

In some examples, as shown in FIG. 6, the thickness S1 of the firstprotrusion 2051 may be set to be within a range from approximately 10 μmto approximately 500 μm, such as 10 μm, 100 μm, 200 μm, 300 μm, 400 μm,or 500 μm. The thickness S1 of the first protrusion 2051 may be referredto the above description. In other words, as shown in FIG. 6, thethickness S1 of the first protrusion 2051 may refer to a maximumthickness of the cross section of the first protrusion 2051 in theprotruding direction of the first protrusion 2051.

It will be noted that setting the thickness of the first protrusion 2051to be too small will increase the manufacturing difficulty, and settingthe thickness of the first protrusion 2051 to be too large will cause athickness of the entire Fresnel projection screen to be increased, whichdoes not satisfy a light and thin requirement of the Fresnel projectionscreen. In some examples, a thickness S2 of the second protrusion 2052may be the same as the thickness S1 of the first protrusion 2051. Asshown in FIG. 6, the thickness S2 of the second protrusion 2052 mayrefer to a difference between the maximum distance S from the surface ofthe second protrusion 2052 facing away from the diffusion layer 202 tothe surface of the diffusion layer 202 facing the second protrusion 2052in the thickness direction of the Fresnel layer 203, and the thicknessS1 of the first protrusion 2051.

Therefore, in some examples, a combined thickness S of the firstprotrusion 2051 and the second protrusion 2052 (i.e., the maximumthickness of the micro-structure layer) may be set to be within a rangefrom approximately 10 μm to approximately 500 μm, such as 10 μm, 100 μm,200 μm, 300 μm, 400 μm, or 500 μm.

In some examples, as shown in FIGS. 5A to 12 and 24, a layer of firstprotrusions 2051 and a layer of second protrusions 2052 are stacked inthe thickness direction OX of the Fresnel layer 203, and are staggeredin the vertical direction OY of the Fresnel projection screen. Thesecond protrusions 2052 are stacked on the first protrusions 2051, sothat light (with a low degree of convergence) passing through two edgesof each first protrusion 2051 in the vertical direction OY is convergedby the second protrusions 2052 again. In this way, the light convergedby the first protrusions 2051 and the second protrusions 2052 may bevery uniform.

For example, edges of a second protrusion 2052 in the vertical directionOY are located on apexes of two first protrusions 2051 adjacent to thesecond protrusion 2052, respectively.

It will be noted that in a case where the protrusions are made of a samematerial, and refractive indexes at different positions are the same anduniform, in order to make each protrusion have the converging effect ofthe convex lens, there is a need to set a surface of the protrusion tohave a non-planar structure, so that there is an optical path differenceamong light passing through different positions on the protrusion. Insome examples, as shown in FIGS. 5A, 8A and 9A, along a directionpointing to the Fresnel layer 203 from the micro-structure layer, adimension of a cross section of each of the first protrusions 2051 andthe second protrusions 2052 in the vertical direction OY of the Fresnelprojection screen decrease. In some other examples, the cross-sectionsof the first protrusions 2051 and the second protrusions 2052 are set ina mirror image manner on a basis of FIG. 5A to form the structure shownin FIG. 7. In this case, the micro-structure layer 205 is providedbetween the transparent base 201 and the diffusion layer 202, and mayalso converge the light.

In some examples, as shown in FIG. 5A, the cross sections of the firstprotrusions 2051 and the second protrusions 2052 perpendicular to theextending direction OZ of the protrusions may have a semicircular shape.In some other examples, as shown in FIGS. 8A, 8B and 8C, the crosssections of the first protrusions 2051 and the second protrusions 2052perpendicular to the extending direction OZ of the protrusions have thetriangular shape. In some other examples, as shown in FIGS. 9A, 9B and9C, the cross sections of the first protrusions 2051 and the secondprotrusions 2052 perpendicular to the extending direction OZ of theprotrusions have the trapezoidal shape. In practical applications, thecross sections of the protrusions may be set according to actual needs.

In some examples, as shown in FIGS. 5A, 6, 8A and 9A, themicro-structure layer 205 includes the first protrusions 2051 and thesecond protrusions 2052 that are stacked. The first protrusions 2051 andthe second protrusions 2052 all extend in the horizontal direction OZ ofthe Fresnel projection screen. A refractive index of the secondprotrusions 2052 is less than a refractive index of the firstprotrusions 2051.

In some examples, the first protrusion 2051 and the second protrusion2052 are made of photosensitive adhesives. For example, the differencein refractive index can be achieved by selecting photosensitiveadhesives of different compositions, or the difference in refractiveindex can be achieved by adjusting the curvature radiuses of the firstprotrusion 2051 and the second protrusion 2052.

In some examples, the first protrusions 2051 in at least one firstmicro-structure layer are the same as the second protrusions 2052 in atleast one second micro-structure layer. For example, the firstprotrusions 2051 in the at least one first micro-structure layer and thesecond protrusions 2052 in the at least one second micro-structure layerhave a same thickness, shape, width, and extending direction.

In some embodiments, in order to better fix the micro-structure layer205, the Fresnel projection screen further includes at least one supportlayer disposed at at least one side of the transparent layer 100. Forexample, as shown in FIG. 10, the at least one support layer includes afirst support layer 2053 disposed on a side of the micro-structure layer205 away from the transparent base 201. For another example, as shown inFIG. 11, the at least one support layer includes a second support layer2054 disposed on a side of the micro-structure layer 205 away from theFresnel layer 203. For another example, as shown in FIG. 12, the atleast one support layer includes the first support layer 2053 disposedon the side of the micro-structure layer 205 away from the transparentbase 201, and the second support layer 2054 disposed on the side of themicro-structure layer 205 away from the Fresnel layer 203. That is, thefirst support layer 2053 and the second support layer 2054 are disposedon both sides of the micro-structure layer 205, respectively. In thisway, the first and second protrusions may be better protected.

According to a refraction law of light, in order to reduce a refractionangle of light passing through the micro-structure layer 205 to convergethe light, in some examples, a refractive index of the first supportlayer 2053 is set to be less than a refractive index of themicro-structure layer 205. The refractive index of the micro-structurelayer 205 may be set to be within a range from approximately 1.58 toapproximately 1.82, such as 1.58, 1.62, 1.7, 1.72, 1.76, 1.78, 1.80, or1.82. The refractive index of the first support layer 2053 may be set tobe within a range from approximately 1.55 to approximately 1.80, such as1.55, 1.58, 1.62, 1.7, 1.72, 1.76, 1.78, or 1.80. Of course, therefractive index of the first support layer 2053 may also be greaterthan a refractive index of the micro-structure layer 205.

The first support layer 2053 may be made of styrene-methyl methacrylatecopolymer (MS), polyethylene terephthalate (PET) or other resinmaterials, and the micro-structure layer 205 may be made of aphotosensitive adhesive or other materials. It will be noted that theabove materials are only described by taking examples, and in practicalapplications, the materials are not limited thereto, as long as therefractive index of the micro-structure layer 205 is greater than therefractive index of the first support layer 2053.

In a case where the micro-structure layer 205 is made of thephotosensitive adhesive, for example, the protrusions with any shapedescribed above may be formed in the mold by using an ultraviolet (UV)curing adhesive; then, the protrusions may be peeled off the mold afterUV curing to be transferred to specified positions in the Fresnelprojection screen. In addition, the protrusions may also be formed byusing a transparent resin material of a traditional lens according to aset shape and a set size, and then are transferred to the projectionscreen.

The support layers located on both sides of the micro-structure layer205 may be formed by means of injection molding, die casting, spraycoating, evaporation or printing.

The first support layer 2053 and the second support layer 2054 may bemade of a same material, and are in direct contact with surfaces of thetransparent layer 100 respectively. In order to facilitate to form thetransparent layer 100, two opposite surfaces of the second support layer2054 may be set to have a planar shape. After the micro-structure layer205 is formed on a surface of the second support layer 2054 facing awayfrom the diffusion layer 202, the first support layer 2053 may be formedby using the coating process, and a surface of the first support layer2053 facing away from the micro-structure layer 205 is made to have aplanar shape, so as to facilitate attachment to the Fresnel layer 203.

In a case where the first support layer 2053 and the second supportlayer 2054 are made of the same material, for example, the first supportlayer 2053 and the second support layer 2054 may be both made of MS, PETor other resin materials.

In some embodiments, in the Fresnel projection screen, the transparentbase 201 may also be replaced with the protective layer or a colorfilter layer, as long as it has a high transmittance to light.

The Fresnel projection screen shown in FIGS. 1 and 2 may resist ambientlight. As shown in FIG. 13, an ambient light resistance principle of theFresnel projection screen is that the ambient light (i.e., light beamsa) is incident onto the surface of the projection screen, a portion ofthe ambient light (i.e., light beams b) is reflected by the Fresnelprojection screen, and another portion of the light (i.e., light beamsc) enters the screen, and then is reflected by the reflective surface ofthe Fresnel layer 203 to form light beams d, and finally exits from thescreen in a form of light beams e. Since the light beams b and the lightbeams e fail to enter human eyes 3, a viewing effect of the viewer isnot affected, that is, the screen has a resistance to the ambient light.

However, when light beams d pass through the diffusion layer 202, asmall portion of the light (i.e., light beams f) may directly enter thehuman eyes 3, which may affect the viewing effect of the viewer(intuitively, reducing a contrast of the image on the screen andwhitening the image). That is, the resistance of the screen to theambient light may be insufficient.

As shown in FIGS. 14 to 17, the Fresnel projection screen in someembodiments further includes at least one spectrally selective layer207.

FIG. 17 shows a spectrally selective layer 207 for a Fresnel projectionscreen, according to some embodiments. As shown in FIG. 17, thespectrally selective layer 207 is located on a side of the Fresnel layer203 away from the diffusion layer 202. For example, the spectrallyselective layer 207 is disposed between the Fresnel layer 203 and thereflective layer 204.

In some examples, the spectrally selective layer 207 is configured toreflect red light, green light and blue light that are in threewavelength ranges respectively, and to absorb at least a portion ofunreflected light. In some other examples, the spectrally selectivelayer 207 is configured to transmit the red light, the green light andthe blue light that are in the three wavelength ranges respectively, andto absorb or reflect light except for the red light, the green light andthe blue light that are respectively in the three wavelength ranges.

In this way, the spectrally selective layer 207 reflects the red light,the green light and the blue light that are in the three wavelengthranges in ambient light reaching the spectrally selective layer 207, andabsorb at least a portion of the unreflected light. As a result, anamount of the ambient light exiting from the diffusion layer 202 is lessthan the amount of light beams d, and thus an amount of the lightentering the human eyes 3 is also less than the amount of light beams f,thereby reducing an influence on the viewing effect of the viewer, i.e.,improving the resistance of the Fresnel projection screen to the ambientlight.

Each region of the spectrally selective layer 207 corresponding to acorresponding pixel in the Fresnel projection screen includes a redfilter sub-region R, a green filter sub-region G and a blue filtersub-region B. The region of the spectrally selective layer 207corresponding to a corresponding pixel in the Fresnel projection screenmay transmit the red light, the green light and the blue light that isin the respective wavelength ranges, and absorb light in otherwavelength ranges.

For example, there are the following several implementations for thearrangement of the red filter sub-region R, the green filter sub-regionG, and the blue filter sub-region B, as shown in FIGS. 19 to 23. Ofcourse, the arrangement of the red filter sub-region R, the green filtersub-region G, and the blue filter sub-region B is not limited thereto,and can be designed according to actual needs.

In a case where the at least one spectrally selective layer 207 isconfigured to transmit the red light, the green light and the blue lightthat are in the three wavelength ranges respectively, and to absorb orreflect the light except for the red light, the green light and the bluelight that are in the three wavelength ranges, the at least onespectrally selective layer 207 may be disposed at at least one of thefollowing positions: a position on the light incident side of thetransparent base 201 as shown in FIG. 14, a position between thetransparent base 201 and the diffusion layer 202 as shown in FIG. 15, ora position between the diffusion layer 202 and the Fresnel layer 203 asshown in FIG. 16.

In a case where the at least one spectrally selective layer 207 isconfigured to transmit the red light, the green light and the blue lightthat are in the three wavelength ranges respectively, and to absorb thelight except for the red light, the green light and the blue light thatare in the three wavelength ranges, the at least one spectrallyselective layer 207 may be disposed between the Fresnel layer 203 andthe reflective layer 204 as shown in FIG. 17.

In some embodiments, as shown in FIGS. 14 and 15, the spectrallyselective layer 207 is disposed at a light incident side of thediffusion layer 202. In the ambient light reaching the spectrallyselective layer 207, only the red light, the green light and the bluelight in three wavelength ranges respectively may pass through thespectrally selective layer 207 and the diffusion layer 202 (light beamsc′), and then form light beams d′ after being reflected by the Fresnellayer 203. The light in other wavelength ranges cannot pass through thespectrally selective layer 207 and the diffusion layer 202. Therefore,the amount of light beams d′ is less than the amount of light beams d,and further the number of light beams f′ directly entering the humaneyes 3 after light beams d′ pass through the diffusion layer 202 is alsoless than the amount of light beams f, thereby reducing the influence onthe viewing effect of the human eyes 3, i.e., improving the resistanceof the Fresnel projection screen to the ambient light.

As shown in FIG. 16, the spectrally selective layer 207 is disposedbetween the diffusion layer 202 and the Fresnel layer 203 of the Fresnelprojection screen. In the ambient light reaching the spectrallyselective layer 207, the red light, the green light and the blue lightthat are in the three wavelength ranges pass through the spectrallyselective layer 207 and then are reflected by the Fresnel layer 203. Atleast a portion of the light in other wavelength ranges is absorbed bythe spectrally selective layer 207. Therefore, the amount of the ambientlight exiting from the diffusion layer 202 is less than the amount oflight beams d, and further the amount of the light entering the humaneyes 3 is also less than the amount of light beams f, thereby reducingthe influence on the viewing effect of the human eyes 3, i.e., improvingthe resistance of the Fresnel projection screen to the ambient light.

In some embodiments, red light, green light and blue light that arerespectively within a wavelength range from approximately 610 nm toapproximately 650 nm, within a wavelength range from approximately 500nm to approximately 540 nm, and within a wavelength range fromapproximately 430 nm to approximately 460 nm are reflected ortransmitted, since the red light, the green light and the blue lightthat are in the three wavelength ranges have pure colors. Therefore, thespectrally selective layer 207 may make a display effect of the image onthe Fresnel projection screen good.

In some embodiments, wavelengths of the red light, the green light, andthe blue light that are in the three wavelength ranges are respectivelywithin a range from approximately 610 nm to approximately 660 nm, withina range from approximately 500 nm to approximately 550 nm, and within arange from approximately 420 nm to approximately 470 nm. As such, thespectrally selective layer 207 may make the Fresnel projection screensuitable for a laser projector capable of emitting light in the abovethree wavelength ranges. FIG. 18 shows a curve of a transmittance of thespectrally selective layer 207, in which T is the transmittance.

In some embodiments, at least a portion of the red light, the greenlight, and the blue light that are in the three wavelength ranges may beselectively reflected or transmitted instead of reflecting ortransmitting all the red light, the green light and the blue light thatare in the three wavelength ranges. For example, red light within thewavelength range from 610 nm to 650 nm is reflected or transmitted, andat least a portion of red light within a remaining wavelength range isabsorbed. Green light within the wavelength range from 500 nm to 540 nmis reflected or transmitted, and at least a portion of green lightwithin a remaining wavelength range is absorbed. Blue light within thewavelength range from 430 nm to 460 nm is reflected or transmitted, andat least a portion of blue light within a remaining wavelength range isabsorbed.

In some embodiments, red light within a wavelength range from 630 nm to650 nm is reflected or transmitted, and at least a portion of red lightwithin a remaining wavelength range is absorbed. Green light within awavelength range from 510 nm to 520 nm is reflected or transmitted, andat least a portion of green light within a remaining wavelength range isabsorbed. Blue light within a wavelength range from 440 nm to 450 nm isreflected or transmitted, and at least a portion of blue light within aremaining wavelength range is absorbed. In the red light, the greenlight and the blue light that are in the three wavelength ranges, thered light, the green light and the blue light that are respectivelywithin the wavelength range from 630 nm to 640 nm, within the wavelengthrange from 510 nm to 520 nm, and within the wavelength range from 440 nmto 450 nm are selected to be reflected or transmitted. In this way, thespectrally selective layer 207 may make the Fresnel projection screensuitable for the laser projector 300 capable of emitting light in theabove three wavelength ranges.

A thickness of the spectrally selective layer 207 of the Fresnelprojection screen is, for example, within a range from approximately 10μm to approximately 200 μm, such as 10 μm, 50 μm, 100 μm, 150 μm or 200μm. As such, on the one hand, the Fresnel projection screen may beprevented from being too thick due to a too thick spectrally selectivelayer, and on the other hand, the resistance of the Fresnel projectionscreen to the ambient light may be prevented from being reduced due to atoo thin spectrally selective layer.

The spectrally selective layer 207 is made of, for example, silicondioxide, lithium fluoride, magnesium fluoride, or of calcium fluoride.In this way, stability of the wavelength selection function of thespectrally selective layer 207 may be improved.

The spectrally selective layer 207 is formed through, for example, avacuum evaporation process. In this way, the forming method may besimpler and easier to implement.

FIG. 24 shows a spectrally selective layer 207 for a Fresnel projectionscreen, according to some embodiments of the present disclosure. Asshown in FIG. 24, the spectrally selective layer 207 is located on thereflective surface of the Fresnel layer 203. The spectrally selectivelayer 207 is configured to reflect the red light, the green light andthe blue light that are in the three wavelength ranges respectively, andto absorb at least a portion of the unreflected light.

Some embodiments of the present disclosure provide a projection system.As shown in FIG. 25, the projection system includes a projector 300configured to project light onto a projection surface 11, and anyFresnel projection screen described above. The Fresnel projection screenhas the projection surface 11 and is configured to receive the lightprojected by the projector 300 and display a corresponding image.

The present disclosure may also provide additional embodiments, and oneor more of components, functions, or structures in the additionalembodiments may be replaced or supplemented by one or more of thecomponents, the functions, or the structures in any Fresnel projectionscreen described above.

The forgoing descriptions are merely specific implementation manners ofthe present disclosure, but the protection scope of the presentdisclosure is not limited thereto. Any person skilled in the art couldconceive of changes or replacements within the technical scope of thepresent disclosure, which shall all be included in the protection scopeof the present disclosure. Therefore, the protection scope of thepresent disclosure shall be subject to the protection scope of theclaims.

What is claimed is:
 1. A Fresnel projection screen, comprising: aFresnel layer; a first micro-structure layer disposed at a lightincident side of the Fresnel layer, the first micro-structure layerincluding a plurality of first micro-structures that are configured todiffusely reflect a portion of light incident thereon and refractanother portion of the light; a second micro-structure layer disposed ona surface of the first micro-structure layer, the second micro-structurelayer including a plurality of second micro-structures that areconfigured to diffusely reflect a portion of light incident thereon andrefract another portion of the light; and a reflective layer disposed ona side of the Fresnel layer away from the first micro-structure layer.2. The Fresnel projection screen according to claim 1, wherein widths,lengths, thicknesses and shapes of the plurality of firstmicro-structures are random, or the plurality of first micro-structureshave a same shape, a same width, a same length and a same thickness;widths, lengths, thicknesses and shapes of the plurality of secondmicro-structures are random, or the plurality of second micro-structureshave a same shape, a same width, a same length and a same thickness. 3.The Fresnel projection screen according to claim 2, wherein each firstmicro-structure and each second micro-structure satisfy at least one ofthe following: a width of each first micro-structure is greater than awidth of each second micro-structure; a length of each firstmicro-structure is greater than a length of each second micro-structure;or a thickness of each first micro-structure is greater than a thicknessof each second micro-structure.
 4. The Fresnel projection screenaccording to claim 1, wherein a refractive index of each of the firstmicro-structure layer and the second micro-structure layer is within arange from 1.3 to 1.8.
 5. The Fresnel projection screen according toclaim 1, wherein the plurality of first micro-structures and theplurality of second micro-structures are projections; a curvature radiusof each first micro-structure is within a range from 50 μm to 500 μm,and a curvature radius of each second micro-structure is within a rangefrom 10 μm to 100 μm.
 6. The Fresnel projection screen according toclaim 1, wherein the second micro-structure layer is an outermost layerof the Fresnel projection screen, and the plurality of secondmicro-structures cover at least part of the first micro-structure layer.7. The Fresnel projection screen according to claim 1, wherein thesecond micro-structure layer is disposed between the firstmicro-structure layer and the Fresnel layer.
 8. The Fresnel projectionscreen according to claim 7, wherein the plurality of firstmicro-structures and the plurality of second micro-structures arestaggered in a vertical direction of the Fresnel projection screen. 9.The Fresnel projection screen according to claim 7, wherein the Fresnelprojection screen further comprises a first support layer disposed on asurface of the second micro-structure layer proximate to the Fresnellayer, and the first support layer is configured to support the secondmicro-structure layer and the first micro-structure layer.
 10. TheFresnel projection screen according to claim 9, further comprising asecond support layer disposed on a surface of the first micro-structurelayer away from the Fresnel layer, wherein the second support layer isconfigured to support the second micro-structure layer and the firstmicro-structure layer.
 11. The Fresnel projection screen according toclaim 10, further comprising a diffusion layer disposed on a side of thefirst micro-structure layer away from the Fresnel layer, wherein thediffusion layer is configured to homogenize the light.
 12. The Fresnelprojection screen according to claim 1, wherein the plurality of firstmicro-structures and the plurality of second micro-structures areprojections extending along a horizontal direction of the Fresnelprojection screen; along a direction pointing to the Fresnel layer fromthe micro-structure layer or along a direction pointing to themicro-structure layer from the Fresnel layer, a dimension, in thevertical direction of the Fresnel projection screen, of a cross sectionof each of the first micro-structures and the second micro-structuresdecreases.
 13. The Fresnel projection screen according to claim 1,further comprising a spectrally selective layer located at a lightincident side of the reflective layer, wherein the spectrally selectivelayer is configured to reflect light with preset wavelength ranges, andto absorb at least a portion of remaining light, or the spectrallyselective layer is configured to transmit the light with the presetwavelength ranges, and to absorb or reflect at least a portion of theremaining light.
 14. A projection system, comprising: a projectorconfigured to project light onto the Fresnel projection screen accordingto claim 1; and the Fresnel projection screen, wherein the Fresnelprojection screen is configured to receive the light projected by theprojector and to display a corresponding image.
 15. A Fresnel projectionscreen, comprising a transparent layer, a color layer, a diffusion layerand a Fresnel layer arranged in sequence along a light incidentdirection; wherein the transparent layer includes: a transparent base;and a micro-structure layer disposed on a light incident surface of thetransparent base and configured to diffusely reflect a portion of lightincident thereon and refract another portion of the light; wherein themicro-structure layer includes a plurality of first micro-structures anda plurality of second micro-structures disposed on a surface of theplurality of first micro-structures; a dimension of each firstmicro-structure is greater than a dimension of each secondmicro-structure, and the dimension includes at least one of a width,length or thickness of a micro-structure.
 16. The Fresnel projectionscreen according to claim 15, wherein a refractive index of thetransparent layer is within a range from 1.3 to 1.8.
 17. The Fresnelprojection screen according to claim 15, wherein the material of thetransparent layer includes at least one of polycarbonate (PC),polyethylene terephthalate (PET), styrene-co-methyl methacrylate (MS),or polymethyl methacrylate (PMMA).
 18. The Fresnel projection screenaccording to claim 15, wherein the transparent layer is bonded to thecolor layer.
 19. The Fresnel projection screen according to claim 15,further comprising a protective layer disposed at a light incident sideof the color layer; wherein the transparent layer is bonded to theprotective layer.
 20. The Fresnel projection screen according to claim15, wherein the plurality of first micro-structures and the plurality ofsecond micro-structures are projections; a curvature radius of eachfirst micro-structure is within a range from 50 μm to 500 μm, and acurvature radius of each second micro-structure is within a range from10 μm to 100 μm.